Jan 2 (Reuters) - It’s the ninth time he’s designed the Olympic downhill ski course, but Bernhard Russi will still feel his nerves tauten when racing gets under way in South Korea next month.

The 69-year-old Swiss knows better than most the excitement of competing at the highest level. He won the Olympic title in 1972 and was narrowly beaten by Austria’s Franz Klammer four years later - the closest any men’s downhill champion has come to making a successful defence of his crown.

Further playing on his nerves, though, is the knowledge of the extreme risks faced by the men and women trying to conquer the course he has set.

“Listen, I used to be a downhiller myself. This will never go away,” Russi told Reuters. “I will always be nervous because somewhere I am always also a little bit afraid, because I know too good that bad things can happen every moment, every time, every day.”

The run-up to these Olympics has highlighted that danger, with the deaths of Frenchman David Poisson and German teenager Max Burkhart in the space of just several weeks in November and December.

While Russi sees the timing as a tragic coincidence, the risk inherent in the sport is a constant.

As he talks about the job of designing courses, it’s clear he sees one of his most vital roles as building in a safety margin for the athletes at the same time as guaranteeing a thrilling spectacle.

“I think in a good downhill I need at least three good jumps. I have to count that the jumps are probably 50 metres long, so I have to be careful that the landing zone is probably 70, 80 metres,” he said.

“If I calculate that with the speed, and the edge and the steepness the racers will jump 50 metres, I have to give them an additional space of 10 to 20 metres for safely landing in case somebody misses the jump completely - then instead of jumping 45 metres he will fly for 70, and I have to make sure that if he makes this mistake he’s not landing on the flat.”

STARTING FROM ZERO

The complexity of the course designer’s task varies hugely from one Olympics to the next, depending on whether there is existing ski infrastructure on the mountain.

The Jeongseon site in South Korea is one of several where Russi has started from zero - when he first went there in 2001, there was “nothing at all. There was a forest road until maybe half-way up and from there nothing, not even a cat walk.”

It was after the Koreans were finally awarded the Games in 2011, at their third attempt, that the Swiss set to work. Since then, he estimates he has visited about 30 times.

The first step is to study the maps, assessing the contours and judging the steepness of the various possible descents. The second is to get his hiking boots on.

“I always say I walk the mountain in order to be able to listen to what the mountain is telling me... Especially in this case, I felt that here is a mountain which has a lot of changing terrains.”

Through his exploration, Russi gets to know the steep and flatter portions, discover the edges and ridges.

“After I know that, I try to build up the story of the mountain. Is it a wild one, or is it a more technical one, or is it more speed or is it more air?”

Sometimes he needs to modify the terrain, for example by filling in a hole or moving some earth to create an adequate landing zone.

But generally he aims to touch the mountain as little as possible. He’s proud that for these Olympics, in the interest of sustainability, agreement was reached to build a single downhill course for men and women - something that hasn’t been done before, but will be repeated when China hosts the Games in 2022.

EXTRA DIFFICULTY

After years of work, the time comes to test the course with the world’s best skiers. Norway’s Kjetil Jansrud won a men’s World Cup downhill here in 2016, and Italy’s Sofia Goggia pipped American Lindsey Vonn in a women’s race last March - victories that should boost their confidence heading into the Games.

But the course will include some new tweaks for the Olympics.

“It has been tested very well but after the test there are always some small changes in course-setting and I think we can add a little bit of difficulty towards the Olympics - so I would say that the course will be more difficult than in 2016,” said Russi.

“It’s going to be a very challenging downhill, a very difficult downhill, a very attractive downhill.”

If he’s done his job well, he will have set the stage next month - as he has so many times before - for what many see as the purest, most thrilling form of winter sports competition.

“You have the top of the mountain, you have the bottom of the mountain, and in between - that’s the challenge,” he said.

“The downhill is the mountain and the man.” (Reporting by Mark Trevelyan; editing by Sudipto Ganguly)